Thermoforming web cutting apparatus

ABSTRACT

A thermoforming web cutting apparatus is provided with a frame with a guide post including a tapered outer surface with increasing cross-sectional dimension toward a closing position, a first support structure with a first cutting die, a second support structure with a second cutting die configured to scissor in intermeshing relation with the first cutting die, and a bushing having a tapered inner surface complementary and reverse to the tapered outer surface on the guide post and adjustable in cross-sectional dimension and configured to guide one of the first support structure and the second support structure for axial reciprocation along the guide post. A method is also provided.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/055,395, which was filed on Feb. 9, 2006, entitled “ThermoformingTrim Press Having Adjustable Bushing Assembly, Trim Tool Guide Assembly,and Method”, naming Jere F. Irwin as inventor, and which is incorporatedby reference herein.

TECHNICAL FIELD

This invention pertains to apparatus and methods for severingthermoformed plastic articles from a sheet of plastic thermoformablematerial. More particularly, the present invention relates to platenposts, tool die posts and bushing assemblies for a thermoforming trimpress.

BACKGROUND OF THE INVENTION

When severing thermoformed articles from a web of plastic material,there exists a need to ensure accurate coaction between male and femalecutting dies in order to ensure accurate part removal, as well as toenhance maximum operating speeds of a thermoforming trim press. Accuratetolerancing and tight fit-up between moving components ensures accuratesevering of articles so that flanges along a trim edge are uniform andprecise. However, small tolerances between sliding parts and accuratefit-up can also result in increased working loads when stroking a trimpress platen or die along a die post (or guide post). Accordingly,improvements are needed in the manner in which moving members of a trimpress are axially guided and fitted for coaction during a cyclicalarticle severing operation.

SUMMARY OF THE INVENTION

An improved platen die set and an improved trim tool die set are eachprovided for a thermoforming trim press with an adjustable bushingassembly. A tapered bushing is mated in complementary relation with atapered die post for the platen die set as well as the trim tool dieset. The taper on each die post decreases in diameter and in an oppositedirection that the taper on an inner surface of the bushing increases.Hence, the bushing conforms with the taper on the die post. Adjustablebushing assemblies enable controlled compression of a bronze bushingonto the tapered die posts so that a tight fit-up is presented at theposition of maximum stroke corresponding with a position where anarticle is severed from a web of thermoformed material. As the trim tooldies are moved apart and as the platens are also moved apart, the taperprovides a relatively looser fit as the platens and the dies separate,which reduces friction between the moving die and platen, and therespective die post during most of the stroke cycle. However, byadjusting the corresponding bushing assemblies, a snug fit-up isprovided between the bushing and the tapered die post at thecorresponding positions of maximum displacement which correspond withthe position at which an article is being severed. Accordingly, anaccurate severing operation is provided while reducing frictional forcesduring the remaining portions of stroke that occur between the platenand its die post, as well as the male punch plate (or trim tool) and itscorresponding die post.

According to one aspect, a thermoforming trim press is provided with aframe, a punch plate, a die plate, and a bushing. The frame has a guidepost including a tapered outer surface with increasing cross-sectionaldimension toward a closing position. The punch plate has a male cuttingdie. The die plate has a female cutting die configured to scissor inintermeshing relation with the male cutting die. The bushing has atapered inner surface complementary and reverse to the tapered outersurface of the guide post. The bushing is adjustable in cross-sectionaldimension and is configured to guide one of the punch plate and the dieplate for axial reciprocation along the guide post.

According to another aspect, a trim tool guide assembly is provided fora thermoforming trim press. The trim tool guide assembly includes aguide post and a bushing assembly. The guide post has a forward-taperedouter circumferential dimension. The bushing assembly has a bushing witha reverse-tapered inner circumferential dimension and an adjustablesupport collar for retaining the bushing assembly and adjusting theinner circumferential dimension of the bushing relative to the outercircumferential dimension of the guide post.

According to yet another aspect, a method is provided for accuratelysevering an article from a web of thermoformed material using athermoforming trim press. The method includes: providing a trim presswith a guide post having a tapered outer surface that increases incross-sectional dimension toward a closing position, a punch plate witha male cutting die, a die plate with a female cutting die configured toscissor with the male cutting die, and a bushing adjustable incross-sectional dimension and having a tapered inner surfacecomplementary and reverse to the tapered outer surface of the guidepost; positioning the male cutting die in intermeshing relation with thefemale cutting die proximate the closing position; and concurrent withpositioning, adjusting cross-sectional dimension of the bushing torealize a desired accurate fit-up between the bushing and the guidepost.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a simplified schematic perspective view of a machine trimpress having alignment and guide features in accordance with thepreferred embodiment of the invention.

FIG. 2 is a vertical side view of the trim press of FIG. 1 andillustrates alignment features on a machine platen die post and a trimtool die post.

FIG. 3 is an end view for an alignment structure on a machine platen diepost.

FIG. 4 is a centerline sectional view of the alignment structure for themachine platen die post of FIG. 3 taken along line 4-4 of FIG. 3.

FIG. 5 is an end view of the alignment structure for use with the trimtool die posts of FIGS. 1-4.

FIG. 6 is a vertical centerline sectional view of the one alternativeconstruction alignment structure of FIG. 5 taken along lines 6-6 of FIG.5.

FIG. 7 is a partial exploded perspective view of the one alternativeconstruction alignment structure of FIGS. 5-6 for use with the trim tooldie posts.

FIG. 8 is a plan view of the trim tool die assembly used within the trimpress and corresponding with the end view of the alignment structure forthe trim tool die post of FIGS. 5-7.

FIG. 9 is a side view of the trim tool die assembly of FIG. 8.

FIG. 10 is a cross-sectional view of the trim tool die assembly takenalong line 10-10 of FIG. 8.

FIG. 11 is a vertical sectional view taken along line 11-11 of FIG. 8illustrating configuration of the male and female cutting diecomponents.

FIG. 12 is an isometric view of the trim tool die assembly of FIGS. 8and 9.

FIG. 13 is an isometric view corresponding with the view taken in FIG.12 of the trim tool die assembly, but illustrating separation betweenthe male and female die members.

FIG. 14 is a vertical centerline sectional view of the bronze bushingused within the alignment structure of FIGS. 5-14.

FIG. 15 is an enlarged view of the bronze bushing from the encircledregion 15 of FIG. 14.

FIG. 16 is an end view of an alternative construction for an alignmentstructure for a trim tool die post corresponding with the view taken inFIG. 5.

FIG. 17 is a vertical centerline sectional view of the alternativeconstruction for an alignment structure of FIG. 16, corresponding withthe view taken in FIG. 6.

FIG. 18 is a partial exploded perspective view of the alternativeconstruction for an alignment structure of FIGS. 16-17, correspondingwith the view depicted in FIG. 7.

FIG. 19 is a simplified perspective view of a second alternativeconstruction for an alignment structure for a trim tool die post overthe two embodiments depicted in FIGS. 1-18.

FIG. 20 is a sectional view taken along lines 20-20 of FIG. 19 andillustrating the alternative construction for the alignment structure ofFIG. 19.

FIG. 21 is a simplified, partial exploded perspective view of thealternative construction for an alignment structure of FIGS. 19-20.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

A preferred embodiment of an improved machine trim press is generallydesignated with reference numeral 10 in FIG. 1. Trim press 10 includes aframe 12 that supports a moving platen 14 and a stationary platen 16. Atrim tool assembly 18 is mounted between moving platen 14 and stationaryplaten 16.

Frame 12 includes a base 20 comprising a ballast tank in which ballastmaterial is placed to stabilize frame 12 while trim press 10 is cycledin operation. For example, gravel can be placed inside base 20.

It is understood that trim press 10 is shown in simplified form in orderto prevent obscuring the invention at hand. More particularly, trimpress 10 comprises one of a number of thermoforming trim pressconstructions. One exemplary construction is disclosed in U.S. Pat. No.6,067,886, herein incorporated by reference, having counterbalancedcrank arm assemblies configured to drive a moving platen inreciprocation. The commercial version of this trim press is availablefrom Irwin Research and Development, of Yakima, Wash., Model No. 44Vertical Trim Station (VTS). Such a trim press supports moving platen 14on a pair of die posts, such as die posts 26 and 28, with fourcounterbalanced crank arm assemblies. Hence, four counterbalancedkinematic linkages (not shown) drive each corner of moving platen 14within frame 12. Details of the kinematic linkages that oscillate platen14 along die posts 26 and 28 are not shown in FIGS. 1 and 2 in order tosimplify the drawings and not obscure the invention at hand. However,any of a number of techniques presently known in the field for driving amoving platen to and fro can be utilized to drive trim press 10 and canbenefit from the improvements presented by the present invention.

A pair of adjustable platen die sets 22 and 24 provide for adjustablesliding fit-up and engagement of moving platen 14 relative to die posts26 and 28. More particularly, die posts 26 and 28 are tapered such thateach die post has a larger diameter when platen 14 is moved intoengagement with stationary platen 16 during a severing operation.According to one construction, each die post 26 and 28 decreases indiameter by 1.5/1000ths of an inch for each inch of length along therespective posts 26 and 28. Accordingly, fit-up in the platen die sets22 and 24 increases the snugness therebetween as the platen 14 is movedinto engagement with platen 16. As platen 16 moves away from platen 14,fit-up loosens, which provides for less friction when moving platen 14.However, the taper in die posts 26 and 28 ensures that there existsaccurate and tight fit-up between the platen die sets 22 and 24 asplatens 14 and 16 come together during a severing operation. It isduring the severing operation (closest positioning between the platens)that precise fit-up is most needed in order to maintain accuratesevering of articles from a web of thermoformable material (not shown).

In operation, trim press 10 receives a web of thermoformable plasticmaterial in which an array of cups has been previously formed within athermoforming machine (not shown). The web is intermittently fed betweenmoving platen 14 and stationary platen 16 by a conveyor (not shown)which intermittently progresses the web through a molding machine wherearticles are formed in the web, and into position between trim pressplatens 14 and 16 where the articles are severed from the web. Trim toolassembly 18 includes male and female cutting members in respective punchplates 34 and die plates 36 that coact to sever articles from the web.

Each platen die set 22 and 24 includes an adjustable bushing assembly 30and 32, respectively. Adjustable bushing assemblies 30 and 32 can betightened to ensure that each bushing assembly 30 and 32 remains tightabout tapered die posts 26 and 28 when moving platen 14 is positioned ata fully extended position towards stationary platen 16. Accordingly, asbushings within bushing assemblies 30 and 32 wear, the bushings can betightened by adjusting bushing assembly 30 and 32 in order to maintainaccurate alignment along tapered die posts 26 and 28.

Trim tool assembly 18 includes a plurality of punches that are providedwithin a male punch plate 34 and a plurality of dies provided within afemale die plate 36. Male punch plate 34 is rigidly affixed to movingplaten 14, whereas female die plate 36 is rigidly affixed to stationaryplaten 16. Accordingly, male punch plate 34 moves in reciprocation withmoving platen 14 by way of kinematic linkages (not shown) that drivemoving platen 14 to and fro along tapered die posts 26 and 28.Additionally, a pair of trim tool die sets 38 and 40 provide foralignment between male punch plate 34 and female die plate 36. Trim tooldie sets 38 and 40 are somewhat similar in construction to platen diesets 22 and 24. The adjustable bushing assemblies 30, 32 and 46, 48 arelikewise similar in operation and set-up.

Trim tool die sets 38 and 40 each have a tapered trim tool die post 42and 44, respectively. Each trim tool die post increases in diameter asthe male punch plate and the female die plate are brought together, andtaper in decreasing diameter as the male punch plate 34 and female dieplate 36 are brought apart. Preferably, respective trim tool die posts42 and 44 are tapered to decrease in diameter by 15/1000ths of an inchfor each axial inch of length along posts 32 and 34. Other alternativeconstructions are also possible. An adjustable bushing assembly 46 and48 has a complementary internal surface taper that substantiallycomplements the taper on posts 42 and 44.

As shown in FIGS. 1 and 2, a pair of accessory guideposts 50 and 52 arealso provided along moving platen 14. However, moving platen 14 does notmount onto guideposts 50 and 52. Instead, guideposts 50 and 52 serve toprovide axial guide ways for accessory devices, such as a treadle or apart handling machine (not shown) that is associated with the trimpress.

FIG. 3 illustrates an outer, left end view of stationary platen 16coincident with tapered platen die post 26.

FIG. 4 illustrates a vertical sectional view of the construction ofplaten die set 22. Platen die set 24 is similarly constructed. Platendie set 22 is mounted between stationary platen 16 and moving platen 14.Die post 26 is tapered to have a larger diameter on the left side and asmaller diameter on the right side. Adjustable bushing assembly 30 isformed from a right half shell 54 and a left half shell 56 that bolttogether with a plurality of threaded fasteners 66 in regions that forma pair of clamp rings. Shells 54 and 56 leave a pair of end gaps whenassembled together. One shell has clearance bores for the fasteners,while the other shell has a threaded bore that mates with the threadedfastener. A pair of bronze bushings 58 and 60 are provided spaced apartwithin bushing assembly 30. Each cylindrical bronze bushing 58 and 60has an inner surface that is frustoconical and complements (or mateswith) the tapered outer surface of tapered platen die post 26. A pair ofcylindrical wicking washers (wool or felt) 62 and 64 are providedadjacent each bronze bushing 58 and 60, respectively, for holdinglubricating oil that is dispensed along die post 26 during reciprocationof bushing assembly 30 therealong.

FIG. 5 illustrates a left end view of female die plate 36 andcorresponds with the trim tool die set 38.

FIG. 6 illustrates tapered trim tool die post 42 which is rigidlyaffixed at one end to female die plate 36. Tapered trim tool die post 42has a larger diameter adjacent female die plate 36, and tapers towards areduced diameter in a direction towards male punch plate 34. Die post 42reciprocates within adjustable bushing assembly 46.

Adjustable bushing assembly 46 includes a tapered bushing housing 68that is affixed to plate 34 via a plurality of cap screw fasteners 70.Housing 68 includes a tapered male threaded portion 74 that includes aplurality of axial slots 72. A tapered lock nut 78 is then tightenedonto tapered male threaded portion 74 via tapered female threads 76 ofnut 78. By advancing nut 78 onto thread 74 and towards plate 34, axialslots 72 accommodate compression on an inner surface of tapered malethreaded portion 74 which compresses a bronze bushing 100 onto tapereddie post 42. Bronze bushing 100 has an inner surface that is tapered soas to complement the opposite taper on die post 42. Bushing 100 canoptionally have an axial slot to enhance compression. When plates 34 and36 are brought to their closest position (during a trim operation), nut78 is tightened onto thread 74 so as to compress bushing 100 radiallyabout die post 42. Subsequently, a lock ring 80 is also threaded ontomale tapered threaded portion 74 via female threads 82. Once lock ring80 is threaded onto threaded portion 74, a plurality of fasteners 83 areengaged with lock nut 78 so as to lock the positioning of lock nut 78onto male threaded portion 74.

A cap 84 is mounted onto tapered bushing housing 68 to entrap bronzebushing 100 radially therein via a plurality of threaded fasteners, suchas cap screws 86.

Trim tool die post 42 also includes a radially outwardly extendingshoulder 88 which engages with female die plate 36 when an end cap 98 isaffixed thereto via a plurality of fasteners 96 (such as cap screws). Alubrication feed fitting 94 communicates with an axial lubricating feedport 90. Feed port 90 communicates with a plurality of radiallyextending ports 92. An oil lubrication line is then connected onto feedfitting 94 to deliver lubricating oil (or grease) via ports 90 and 92 toouter surfaces of trim tool die post 42 to lubricate axial slidingmovement between an inner surface of bronze bushing 100 and an outersurface of trim tool die post 42.

FIG. 7 illustrates in greater detail the construction of trim tool dieset 38. Punch plate 34 and die plate 36 are shown in simplified form asa rectangle (with remaining portions omitted). Exploded viewconstruction of trim tool die set 38 illustrates the components andassembly of tapered, bronze bushing 100 onto tapered trim tool die post42. Tapered bushing housing 68 is affixed onto plate 34 using aplurality of threaded cap screw fasteners 70. Bronze bushing 100 isentrapped within tapered bushing housing 68 via a cap ring 84 and aplurality of threaded cap screw fasteners 86.

FIG. 8 illustrates in plan view the trim tool assembly 18. FIG. 9illustrates the trim tool assembly 18 in side view. FIG. 10 illustratestrim tool assembly 18 taken along line 10-10 of FIG. 8.

FIG. 11 illustrates a cross-sectional view of trim tool assembly 18taken through line 11-11 of FIG. 8 corresponding with a cross-sectionalview taken through a punch and die of punch plate 34 and die plate 36,respectively.

FIG. 12 illustrates a perspective view of trim tool assembly 18 whenplates 34 and 36 are brought together. More particularly, plates 34 and36 are temporarily held together with a plurality of cross-members thatare removably fastened on opposite ends of plates 34 and 36 tofacilitate insertion and removal of trim tool assembly 18 betweenplatens on a trim press.

FIG. 13 illustrates trim tool assembly 18 when plates 34 and 36 are at amaximally spaced-apart position during a trim operation. Suchpositioning corresponds with trim tool die sets 38 and 40 beingpositioned at the most tapered, or reduced diameter, position on eachrespective die post 42 and 44.

FIG. 14 illustrates a centerline sectional view of bronze bushing 100.An outer diameter of bronze bushing 100 is uniform. However, a rightmostinner diameter portion is smaller than the leftmost inner diameterportion of bronze bushing 100, corresponding with the inner diametertaper provided therein which complements the decreasing taper of therespective die posts extending from a leftmost position (largerdiameter) to a rightmost position (smaller diameter).

FIG. 15 illustrates an array of circumferential grooves 101 that areprovided on an inner surface of bronze bushing 100 to facilitateconveyance and retention of lubricating fluid, or oil, along an innersurface of bronze bushing 100 as bronze bushing 100 axially travelsacross a respective tapered die post. Optionally, grooves 101 can have ahelical shape, or they can be eliminated.

FIGS. 16-18 provide an alternative construction for a trim tool die set38 of FIGS. 5-7. FIG. 16 illustrates a left end view of platen 16.

FIG. 17 illustrates an alternative construction of trim tool die set 138similar to die set 38 of FIG. 6. However, a tapered bushing housing 168differs in that bushing housing 168 has a longitudinal slot 173 providedin a circumferential body 171 (see FIG. 18). A threaded fastener 175 isused to compress housing 171 by threading fastener 175 into a threadedbore in housing 171 across slot 173 which closes slot 173 and clampsbronze bushing 100 onto tapered die post 142.

FIGS. 19-21 illustrate a second alternative construction for analignment structure for a trim tool die set 238 similar to die set 138in FIG. 17 and die set 38 in FIG. 6. More particularly, a taperedbushing housing 268 differs from tapered bushing housing 168 (of FIG.17) in that bushing housing 268 has a longitudinal slot 273 that isadjusted in thickness (or gap size) by tightening and loosening a pairof threaded cap head screws 275 in order to compress a bronze bushing200. By tightening threaded screws (or fasteners) 275, bushing housing268 is provided with an aperture that is adjustably reduced in diameterso as to compress bushing 200 by decreasing the thickness of slot 273 inorder to clamp bronze bushing 200 onto tapered die post 242. Inresponse, bushing 200 deforms so as to adjust fit-up with guide post242.

FIGS. 20 and 21 further illustrate the construction and assembly ofbearing 200 within housing 268. An inner surface of bearing 200 has atapered inner surface that mates in complementary and opposed relationwith a corresponding tapered surface provided on an outer surfaceportion of tapered die post 242. Post 242 is affixed onto a female dieplate 36 (see FIG. 19) via an end plate 298 using a plurality ofthreaded cap screws 293. Housing 268 is affixed onto a male punch plate34 via a ring backing plate 299 having a radial slot 291 via a pluralityof threaded fasteners 297. Additionally, a plurality of radiallyspaced-apart threaded fasteners 295 further secure housing 268 onto malepunch plate 34.

Although the embodiments depicted in FIGS. 1-21 illustrate a lubricationsystem for delivering lubrication between a bearing and a guide post,such as a die post, it is understood that it is not necessary to deliverlubrication therebetween. For example, the bushing and/or the guide rodcan be constructed of a relatively low friction material, such as byconstructing the bushing from bronze material.

In the case where lubrication is used, one preferable lubricationcomprises a oil which is delivered through a pressurized oil feed systembetween each bearing and guide rod. Alternatively, other lubricationscan be utilized, such as grease, graphite, or other lubricating medium.

According to one construction, the collars or housings for each bushingassembly can be constructed from No. 836 standard steel, and the guiderods are constructed from pre-heat-treated 4130 steel that is inductionhardened to approximately 60 Rockwell, and is then covered with a thin,dense chrome outer surface.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A thermoforming web cutting apparatus, comprising: a frame with aguide post including a tapered outer surface with increasingcross-sectional dimension toward a closing position; a first supportstructure with a first cutting die; a second support structure with asecond cutting die configured to scissor in intermeshing relation withthe first cutting die; and a bushing having a tapered inner surfacecomplementary and reverse to the tapered outer surface on the guide postand adjustable in cross-sectional dimension and configured to guide oneof the first support structure and the second support structure foraxial reciprocation along the guide post.
 2. The thermoforming webcutting apparatus of claim 1, wherein the thermoforming web cuttingapparatus is a thermoforming trim press.
 3. The thermoforming webcutting apparatus of claim 1, wherein the bushing comprises acompressible bushing.
 4. The thermoforming web cutting apparatus ofclaim 3, further comprising a compression collar encompassing thebushing and configured to compress the tapered inner surface of thebushing.
 5. The thermoforming web cutting apparatus of claim 4, whereinthe bushing comprises a bronze bushing.
 6. The thermoforming web cuttingapparatus of claim 5, wherein the bushing comprises a plurality ofcircumferential grooves provided in the inner surface of the bushing. 7.The thermoforming web cutting apparatus of claim 6, wherein the guidepost comprises at least one lubrication feed port configured to deliverlubrication between the inner surface of the bushing and the outersurface of the guide post.
 8. The thermoforming web cutting apparatus ofclaim 7, wherein the at least one lubrication feed port comprises anaxial lubrication feed port and at least one radially extendinglubrication feed port communicating with the axial lubrication feedport.
 9. The thermoforming web cutting apparatus of claim 1, furthercomprising a housing having a circumferential body with a slot providedin the body, the housing configured to support the bushing, and at leastone fastener configured to adjustably compress the body to decreasewidth of the slot in order to compress the bushing about the guide post.10. The thermoforming web cutting apparatus of claim 1, furthercomprising a housing configured to compress the bushing and adjustfit-up between the bushing and the guide post.
 11. The thermoforming webcutting apparatus of claim 10, wherein the housing comprises a pair ofshells configured to mate together in complementary relation about thebushing and at least one fastener configured to draw together the shellsto compress the bushing.
 12. The thermoforming web cutting apparatus ofclaim 11, wherein the housing comprises a tapered male thread portion, aplurality of axial slots provided in the tapered male thread portion,and a tapered lock nut having a tapered female thread portion configuredto engage in complementary relation with the tapered male thread portionand adjustable with respect to the tapered male thread portion tocompress the tapered male thread portion so as to compress the bushingcontained therein.
 13. The thermoforming web cutting apparatus of claim1, wherein the tapered outer surface of the guide post complements, inopposed relation, the tapered inner surface of the bushing.
 14. Thethermoforming web cutting apparatus of claim 13, wherein the bushingcomprises at least one axial slot configured to accommodate dimensionalchanges during compression of the bushing about the guide post.
 15. Aweb cutting assembly for a thermoforming web cutting press, comprising:a guide post having a forward-tapered outer circumferential dimension;and a bushing assembly with a bushing having a reverse-tapered innercircumferential dimension and an adjustable support collar for retainingthe bushing and adjusting the inner circumferential dimension of thebushing relative to the outer circumferential dimension of the guidepost.
 16. The web cutting assembly of claim 15, wherein the web cuttingassembly is configured for use on a thermoforming web trim press. 17.The web cutting assembly of claim 15, wherein the bushing is made from aductile material.
 18. The web cutting assembly of claim 17, wherein theadjustable support collar is configured to compress the bushing in orderto adjust the inner circumferential dimension of the bushing.
 19. Theweb cutting assembly of claim 17, wherein the adjustable support collarcomprises a tapered bushing housing having a threaded male portion, acap ring having a threaded female portion complementary with thethreaded male portion of the housing, and a plurality of fastenersconfigured to affix the cap ring onto the bushing housing.
 20. The webcutting assembly of claim 17, wherein the bushing comprises a bronzebushing.
 21. The web cutting assembly of claim 15, wherein the guidepost comprises at least one lubrication feed port extending through theguide post to deliver lubrication to the outer circumferential dimensionof the guide post.
 22. The web cutting assembly of claim 21, wherein theat least one lubrication feed port comprises an axial feed port and atleast one radial feed port communicating with the axial feed port todeliver lubrication to the outer circumferential dimension of the guidepost.
 23. The web cutting assembly of claim 22, wherein the bushingcomprises an inner circumferential surface including an array ofcircumferential grooves provided therein for retaining lubrication. 24.The web cutting assembly of claim 23, wherein the bushing comprises abronze bushing.
 25. The web cutting assembly of claim 15, wherein theguide post comprises a frustoconical outer surface.
 26. The web cuttingassembly of claim 25, wherein the bushing comprises a frustoconicalinner surface having an array of circumferential grooves providedtherein.
 27. A method for accurately severing thermoformed web materialusing a thermoforming web cutting apparatus, comprising: providing a webcutting apparatus with a guide post having a tapered outer surface thatincreases in cross-sectional dimension toward a closing position, afirst member with a first cutting die, a second member with a secondcutting die configured to scissor with the first cutting die, and abushing adjustable in cross-sectional dimension and having a taperedinner surface complementary and reverse to the tapered outer surface ofthe guide post; positioning the first cutting die in intermeshingrelation with the second cutting die proximate the closing position; andadjusting cross-sectional dimension of the bushing to realize a desiredaccurate fit-up between the bushing and the guide post.
 28. The methodof claim 27 further comprising moving apart the first member and thesecond member away from the closing position so as to reposition thebushing along the guide post away from the closing position so as toloosen fit-up between the bushing and the guide post.
 29. The method ofclaim 28, wherein moving the bushing relative to the guide post into aposition away from the closing position reduces friction between thebushing and the guide post.
 30. The method of claim 27, furthercomprising reciprocating the first member relative to the second memberbetween open and closed positions.